period and disk radius changes in the dwarf nova IP Pegasi

We present UBVRI observations of 49 eclipses of the dwarf nova IP Peg obtained during a long term observing campaign between July 1990 and December 1991. We combine these data with previously published ones in order to study long term period variations and to measure changes in disk radius associate...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 1993-06, Vol.273 (1), p.160-168
Main Authors: WOLF, S, MANTEL, K. H, HORNE, K, BARWIG, H, SCHOEMBS, R, BAERNBANTNER, O
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
Novae, dwarf novae, recurrent novae, and other cataclysmic (eruptive) variables
Stars
Variable and peculiar stars (including novae)
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Summary:We present UBVRI observations of 49 eclipses of the dwarf nova IP Peg obtained during a long term observing campaign between July 1990 and December 1991. We combine these data with previously published ones in order to study long term period variations and to measure changes in disk radius associated with the dwarf nova outbursts. Analysis of white dwarf egress timings from 1984-1991 shows that the 3.8 h orbital period varies sinusoidally with a period of 4.7 yrs. This change can be explained by a third body (late M dwarf) with a most probable mass of 0.10 M. Attempts to explain the change in period by magnetic activity on the secondary star fail, because the required variation in luminosity of the secondary is not observed. From measurements of hot spot ingress and egress timings we determine a mass ratio q = M2/Mi of 0.6 and a steadily decreasing disk radius during decline from outburst.
ISSN:0004-6361
1432-0746